This core provides administrative, biostatistical, epidemiologic, health economics, technical assistance, and computer science support to all projects of this proposal. It continues the functions it has served effectively over the first 20 years of the ARAMIS Project and builds a platform for proposed and future work. This Core is responsible for central outcome assessment, data quality control and follow-up activities. It has responsibility for rigorous and timely performance of all Project tasks, and monitors each project from inception through patient recruitment, outcome assessment by Health Assessment Questionnaire (HAQ), data quality control, analyses, manuscript preparation, and publication. It develops and provides the common dictionaries, instruments, and project protocols. In this Core, representing ARAMIS continuity, we fully develop the history of productive collaboration between Program Investigators over the years, the contributions of ARAMIS to development of the research questions to be addressed, and specify our general approaches to biostatistical and health economics analyses.